Last major update issued on May 4, 2010 at 04:20 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update April 2, 2010)]
The geomagnetic field was unsettled to minor storm on May 3. Solar wind speed ranged between 575 and 794 km/s under the influence of a high speed stream from CH402.
Solar flux measured at 20h UTC on 2.8 GHz was 80.3. The planetary A index was 27 (STAR Ap - based on the mean of three hour interval ap indices: 27.4). Three hour interval K indices: 55443334 (planetary), 55444323 (Boulder).
The background x-ray flux is at the class A6 level.
At midnight there were 4 spotted regions on the visible solar disk.
Region 11063 reemerged with a single small spot.
Region 11066 developed slowly and quietly.
Region 11067 was mostly unchanged.
New region 11068 rotated into view at the southeast limb.
May 1-3: No obvious Earth directed CMEs were observed in LASCO or STEREO images.
Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago
A well defined recurrent coronal hole (CH402) in the northern hemisphere was in an Earth facing position on April 30 and May 1.
Processed SOHO/EIT 195 image at 23:48 UTC on May 3. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is very poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to active on May 4. Quiet conditions are likely on May 5-7.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived the
color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Compare to the previous day's image
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
| Active region | Date numbered | SWPC spot count |
STAR spot count |
Location at midnight | Area | SWPC Classification |
Comment |
|---|---|---|---|---|---|---|---|
| 11063 | 2010.04.28 | 2 | 1 | N18W52 | 0010 | BXO | classification was AXX at midnight |
| 11064 | 2010.04.30 | N15W11 | plage | ||||
| 11065 | 2010.05.02 | 1 | S32W29 | 0000 | AXX | spotless | |
| 11066 | 2010.05.02 | 5 | 5 | S27E05 | 0020 | CRO | |
| 11067 | 2010.05.02 | 2 | 3 | N23E38 | 0020 | CSO | classification was DSO at midnight, area 0030 |
| 11068 | 2010.05.03 | 1 | 1 | S19E76 | 0000 | AXX | classification was HRX at midnight, area 0020 |
| Total spot count: | 11 | 10 | |||||
| SSN: | 61 | 50 | |||||
| Month | Average measured solar flux | International sunspot number (SIDC) | Smoothed sunspot number | Average ap (3) |
|---|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
|
| 2000.07 | 202.3 | 170.1 | 119.8 | |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) | |
| 2008.07 | 65.7 (SF minimum) | 0.5 | 2.8 (-0.4) | |
| 2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
3.25 |
| 2009.03 | 69.2 | 0.7 | 2.0 (+0.1) | 4.85 |
| 2009.04 | 69.7 | 1.2 | 2.2 (+0.2) | 4.52 |
| 2009.05 | 70.5 | 2.9 | 2.3 (+0.1) | 4.75 |
| 2009.06 | 68.6 | 2.6 | 2.7 (+0.4) | 5.22 |
| 2009.07 | 68.2 | 3.5 | 3.6 (+0.9) | 5.49 / 4.55 |
| 2009.08 | 67.3 | 0.0 | 4.8 (+1.2) | 5.70 / 4.89 |
| 2009.09 | 70.5 | 4.2 | 6.1 (+1.3) | 3.88 / 3.61 |
| 2009.10 | 72.6 | 4.6 | 7.0 (+0.9) | 3.66 / 3.56 |
| 2009.11 | 73.6 | 4.2 | (7.7 predicted, +0.7) | 2.45 / 2.63 |
| 2009.12 | 76.7 | 10.6 | (8.9 predicted, +1.2) | 1.41 / 1.92 |
| 2010.01 | 81.1 | 13.1 | (10.2 predicted, +1.3) | 2.93 / 3.07 |
| 2010.02 | 84.7 | 18.6 | (11.8 predicted, +1.6) | 4.15 / 4.61 |
| 2010.03 | 83.4 | 15.4 | (13.7 predicted, +1.9) | 4.58 / 4.65 |
| 2010.04 | 75.9 | 7.9 | (15.3 predicted, +1.8) | 10.22 |
| 2010.05 | 79.2 (1) | 3.9 (2) | (16.6 predicted, +1.3) | (23.29) |
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SWPC) sunspot number. The official international sunspot number is typically
30-50% lower.
3) Running average based on the
daily SWPC ap indices. Values in red are based on
official NGDC ap indices.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.